Maps, Navigation, and the Real World

Introduction

Backpacking navigation with a map essentially involves reading a set of abstract conceptions of physical coordinates onto the real terrain. The abstractions are your map and your goal.

These abstractions are much more than "conceptions," as the coordinate-contour system your map is based on is almost a perfect example of abstract mathematical and visual representations capable of almost perfectly describing your personal position in the real physical world.

I say "almost" perfectly because we still have not figured out how to display a 3-D spherical map representation accurately on a 2-D flat paper map. Distortions occur.

The first "real terrain" we want to initially navigate our way across is composed of the main trails between Lake Tahoe and Mount Whitney, so we will mainly use the maps to locate ourselves in the terrain. This will allow us to easily estimate distances, and of especially importance, allow us not get confused by the many unmarked trail junctions we will encounter as we hike down the trails. Many of these junctions are well-trod, making a correct decision more difficult.

Later we will use map and trail skills to find and follow un maintained sections of trail. Our map reading skills will develop to show us where we can execute exciting local scrambles from campsites along the trails between Lake Tahoe and Mount Whitney that we have pre-selected. We have packed an extra day's food for each section between resupply points to support a day's scrambling & exploration.

The final goal of developing and improving our navigation skills is to eventually navigate sections of the Sierra Crest or Sierra Flanks on your own cross-country routes, as well as to develop the capacity to follow "popular" cross-country routes, such as Roper's High Sierra Route.

Orientation

The navigation skills we seek to learn here start from locating your position a map, across understanding the relationship of the elevation of the North Star to our latitude, to the subsequent relationship of True North to magnetic North, including the rise and setting positions of stars and our Sun upon their shifting tracks. I seek to understand the use of all of these observable natural reference points as well as the man-made tools, maps and compass, that can help me describe my exact position in time and space.

The whole goal is to get you oriented with your terrain, comfortable and familiar with reading the observable astronomical reference points provided by nature, familiar with reading various maps, and capable of generating excellent analysis and making good decisions based on these observations. Thus the maps are not the only piece of the puzzle: you also must be able to accurately measure time as well, especially the amount of hours until local sunset.

All of these observed relationships can be described mathematically on a map, and these observations, or the abstract numbers that represent them, can bring you to your desired location. I strongly suggest building navigation skills from a "ground-up" position, building personal navigation skills, confidence, and competence as you develop your general backpacking trail and camp skills along with your overall fitness.

NO GPS

I use no GPS, nor will any of the exercises or lessons following include GPS. The reasons are simple and two-fold. First, an experience I had with GPS hikers who were over-relying on their GPS to their great detriment, and second, you'll really wish you actually personally possessed fundamental navigation and trail skills when your GPS breaks, runs out of batteries, or is otherwise disabled.

Maps, Navigation, and the Real World

Now the question is what to do with all the astronomical information linked to above. That depends on your goal. I never bring a watch, GPS, or other electronic gear into the wilderness.

Clock and Compass

My goal is to establish the position of the Sun as my trail clock and part-time compass. To do this I will have to record astronomical information from the links above to use on the trail.

Though the Sun will be a clock all day long, it will only act as a compass at Sunrise and Sunset, when these points reveal an exact compass bearing as well as the precise time. I can begin and end the days knowing exactly what time it is, and how the terrain sits in relation to the compass without a compass.

Between Sunrise and Sunset is 12 Noon. 12 Noon is defined astronomically as the time when the Sun is at its highest point at your specific location. This position of the Sun can be found with your compass. When the Sun bisects the North-South line on your compass it is 12 Noon at your local position, whatever the clock says.

You can determine the "clock" time for when the Sun is directly above your position from the astronomical charts linked to above, so you will know both the time of local noon as well as the official "clock" time when the Sun is at its highest point. During Daylight Savings Time this gets a bit confusing.

Recording the exact times and position of the Sun at Sunrise, Sunset, and High Noon gives you the ability to determine time and direction from astronomical sources. You can easily measure time after Sunrise, before or after Noon, or how many hours you have until sunset.

Each hour the sun travels 15 degrees. It so happens that the size of a fist at arms length equals 15 degrees. This means that you can hold out your fist at the end of your arm (looking at the back of your hand's width, not including the thumb) and measure time: Now you can easily measure how many hours the sun is before or after noon, or how many hours it will be to local Noon or astronomical sunset.

This also works well for tracking time at night. Pick a star near the Eastern horizon at sunset. Note its height above the horizon at sunset. Now you can measure out each hour after sunset by measuring the rise of this star above its start point: It will move 15 degrees, or the width of your fist at arm's length every hour.

A drawback of these natural reference points is that they can be obscured by fog, clouds, and storms. That's why you bring a compass...

The Trail Journal and Trail Notes

Now you have to make the astronomical information useable. I have a 15 page nature guide that I printed up on 8 x 11 paper. It is for identifying rees, bushes, flowers and such. I fold the nature guide into quarters and keep it in a waterproof zip-lock plastic bag within easy reach inside my buttpack next to my camera.

The backside of this nature guide gives me 15 blank pages for my journal and trail notes. This way I can quickly take pictures or notes, or both, as I hike down the trail. I have to make sense of my notes when I get back, and the astronomical information I record has to be usable, so I have developed a clear format for my Trail Journal and Notes.

I label the top blank page with the name of the trip, the season, the date, and basic notes about the present and predicted weather along with any particular concerns about the trip.

I then note the precise compass points and times of sunrise and sunset, derived from the links provided above. For trips over a week in duration I record the information for the first and last days of the trip to maintain accurate astronomical information over the span of the trip. The reason for two sets of figures is that the sunrise and sunset times shift slowly every day.

I add to this the "clock" time and elevation (above the Southern Horizon) of the Sun at local noon, when the sun is at its highest daily position crossing the North-South line on your compass.

Physical Time

Using these figures I can now figure out the exact times and compass points at Sunrise and Sunset, determine both the time of local Noon and translate that local time into Pacific Daylight Time, and easily use my fist to determine the exact time of day between Sunrise and Sunset, as well as measure the number of hours I have to sunset.

Understanding the physical nature of time allows me to estimate how many miles I can get during the day, and especially how many hours I have until the sinking Sun forces me to make camp.

All of this can be done by recording some basic information, bringing a compass, and having a fist at the end of one of your arms.

As I don't bring a phone, I also record the telephone numbers of my Sister, who is monitoring my backpacking trip's entrance and exit dates, as well as any local friends I am going to call and visit after the trip.

Some Basic Facts

The North Star is less than 2 degrees off of true North. This means that the North Star is much more accurate than your compass, which is typically off by 15.5 degrees at our latitude. (Call my local latitude 33 degrees North.) The reason for this is that the location of the Magnetic North Pole is offset to the East of True North from our location in North America.

Wikipedia article about Magnetic North.

Wikipedia article about Magnetic Declination.

NOAA Find your Local Declination.

NOAA Geomagnetism FAQ

USGS Geomagnetism FAQ

Magnetic North (North on your compass) is offset from the True North Pole by an angle that depends on your latitude and longitude. The angular and mileage difference between Magnetic North to True North is indicated on every good map you use.

The height of the North Star above the horizon is exactly equal to your Latitude.

Maps, Navigation, and the Real World

Instructional Materials

Lets get some more resources for you to check out.

Sarge Faria has an excellent series of navigation and map reading videos on his YouTube channel that I organized into a playlist.

Check out the playlist of Sarge Faria's Navigation Videos on the TahoetoWhitney YouTube Channel